Fuse holder

ABSTRACT

A fuse holder including first and second tubular members arranged in tandem, a cap engageable with the upper end of the first tubular member, a cylindrical electrical terminal and coupling threaded to the lower end of the first tubular member and to the upper end of the second tubular member, and a plug type electrical terminal which is threaded to and seals off the lower end of the second tubular member. When the cap is engaged with the first tubular member and O-ring seal between the cap and the first tubular member and O-ring seals adjacent to each of the threaded engagements provide a hermetically sealed fuse enclosure. The cap includes an axially extending elongated member having an elastic member secured to its end for engaging the hollow contact end of a fuse. Further, the cap includes a plurality of spaced apart teeth extending radially inwardly and the upper end of the first tubular member includes a plurality of spaced apart and radially extending beveled teeth. The cap teeth are engageable with the beveled surfaces on the teeth of the first tubular member such that rotation of the cap in one direction axially moves the cap to insure a tight locking engagement between the cap and tubular member. Thereafter, rotation of the cap in an opposite direction unlocks the cap so that it can be lifted away from the first tubular member. When the fuse is in the seated position, a toroidal spring connects one contact of the fuse to the tubular electrical terminal and a second toroidal spring connects the other contact of the fuse to the plug-type terminal.

United States Patent Caione FUSE HOLDER [76] Inventor: Vincenzo Caione, 265 Salita Tarsia,

Naples, Italy 22 Filed: Feb. 12, 1973 211 Appl. No.: 331,420

Primary ExaminerJ. D. Miller Assistant ExaminerFred E. Bell Attorney, Agent, or Firm-Breitenfeld & Levine 5 7 ABSTRACT A fuse holder including first and second tubular members arranged in tandem, a cap engageable with the upper end of the first tubular member, a cylindrical electrical terminal and coupling threaded to the lower [11] 3,835,432 Sept. 10, 1974 end of the first tubular member and to the upper end of the second tubular member, and a plug type electrical terminal which is threaded to and seals off the lower end of the second tubular member. When the cap is engaged with the first tubular member and O- ring seal between the cap and the first tubular member and O-ring seals adjacent to each of the threaded engagements provide a hermetically sealed fuse enclosure. The cap includes an axially extending elongated member having an elastic, member secured to its end for engaging the hollow contact end of a fuse. Further, the cap includes a plurality of spaced apart teeth extending radially inwardly and the upper end of the first tubular member includes a plurality of spaced apart and radially extending beveled teeth. The cap teeth are engageable with the beveled surfaces on the teeth of the first tubular member such that rotation of the cap in one direction axially moves the cap to insure a tight locking engagement between the cap and tubular member. Thereafter, rotation of the cap in an opposite direction unlocks'the cap so that it can be lifted away from the first tubular member. When the fuse is in the seated position, a toroidal spring connects one contact of the fuse to the tubular electrical terminal and a second toroidal spring connects the other contact of the fuse to the plugtype terminal.

10 Claims, 5 Drawing Figures FUSE HOLDER The subject invention relates to fuse holders, and in particular to a fuse holder which is especially useful for housing fuses used with transformers forming part of underground electrical systems.

Underground electrical systems often include transformers filled with oil. A fuse which protects such a transformer is usually arranged within the transformer. To isolate the fuse from the oil inside the transformer, as well as from all other deleterious agents such as humidity and dust, the fuse is placed into a fuse holder which itself is immersed in the oil.

Typically, the fuse holders include removable caps which when removed permit the replacement of spent fuses. These caps are complex devices because when they are in place they must provide a hermetic seal between the cap and the rest of the fuse holder.

It is an object of the present invention to provide a fuse holder having a simple cap structure for providing access to a fuse within the holder, and a hermetic seal between the cap and the holder.

It is another object of the present invention to provide an improved hermetically sealed fuse holder capable of withstanding high pressures and temperatures created by the hot oil inside the transformer, so that no oil can leak into the fuse holder.

By way of summary, a hermetically sealed holder for a fuse, according to the invention, comprises: first and second axially-aligned tubular members, a first cylindrical electrical terminal engaging one end of the first tubular member and the adjacent end of the second tubular member, means for closing off the other end of the first tubular member and for inserting and removing the fuse from the fuse holder, and a second electrical terminal mechanically coupled to the other end of the second tubular section.

The above-mentioned and other objects of this invention will become apparent by reference to the following description and the accompanying drawings, in which:

FIG. 1 is an elevational view of a fuse holder, according to the invention, mounted in a partly-shown transformer housing;

FIG. 2 is a cross-sectional view of the fuse holder taken along line 22 in FIG. 1;

FIG. 3 is an exploded perspective view of the cap of the fuse holder and the end of the fuse holder body with which it is engageable;

FIG. 4 is a cross-sectional view of the fuse holder taken along line 44 in FIG. 1; and

FIG. 5 is a cross-sectional view of the fuse holder taken along line 55 in FIG. 1.

FIG. 1 shows a fuse holder 10, according to the invention, operatively positioned with the major portion of its body within a transformer housing 11. Generally, the fuse holder includes a cap 12 which is engageable with the upper end of a tubular member 13. The lower end of the tubular member 13 is connected by an internal thread to a cylindrical electrical terminal or coupling 14, which, in turn, is connected to the upper end of a second tubular member 15. The lower end of the tubular member includes an internal thread which supports a plug-type electrical terminal 16. 6

electrical terminal 16, provide a cylindrical body 17 (see FIGS. 25). The electrical terminals 14 and 16 are preferably metallic, and the cap 12 and tubular members 13 and 15 are molded from a synthetic resin, preferably one containing nylon and fiberglass such as is sold under the trademark Zytel 7lG-33" by E. I. Dupont de Nemours & Co., Inc. The use of these materials, in conjunction with hermetic seals, more fully described below, between the terminals 14 and 16 and the tubular members 13 and 15 render the enclosure 17 impervious to the oil located within the housing 11 even under high pressures and temperatures.

More specifically, referring to FIG. 2, electrical terminal 14 includes a centrally located outwardly projecting flange 18, an external thread 19 running from one side of the flange 18 to one of its ends, and another external thread 20 running from the other side of the flange to its other end. Thread 19 is engageable with an internal thread 21 located in tubular member 13. Threads 19 and 21 are of sufficient length to permit, when assembled, the lower end edge 22 of the tubular member 13 to compress an O-ring seal 23, preferably made of neoprene, against the flange 18. The threaded engagement between the tubular member 13 and the electrical terminal 14 and the use of the O-ring seal 23 provides a hermetic seal which, if desired, may be improved by the application of an adhesive to the threads 19 and 21 during assembly. Similarly, tubular member 15 includes a thread 24 which is engageable with the thread 20 of the electrical terminal 14. When the parts are assembled, the upper end edge 25 of the tubular member 15 compresses an O-ring seal 26, preferably made of neoprene, against the flange 18 of the electrical terminal 14 to provide another hermetic seal.

Referring to FIG. 5, the plug-type terminal 16 includes a bore 28 extending into its upper end, and an external thread 29 running from that end to a flange 30 located at its lower end. Tubular member 15 includes an internal thread 31 which is engageable with thread 29 and threads 29 and 31 are of such a length that when engaged, the lower end edge 32 of member 15 compresses an O-ring seal 33, preferably made from neoprene, against the flange 30. Thus, the threaded engagement of the tubular member 15 with terminal 16 and their engagement with the O-ring seal 33, provide a hermetic seal. As previously mentioned, the seal may be improved by the use of an adhesive between the threads 29 and 31.

Referring to FIGS. 3 and 4, cap 12 includes a cavity into which an annular boss 35 extends downwardly, an O-ring seal 36, preferably made of neoprene, being seated within a circular groove formed in the lower face of the annular boss 35. A plurality of spaced teeth 37 extend inwardly from the lower edge of the cap. Tubular member 13 includes at its top end a plurality of spaced teeth 38 extending radially outwardly, a portion of the lower face of each tooth 38 being beveled at 39. Thus, if the cap 12 is moved downwardly, as indicated by the arrow 40 in FIG. 3, so that its teeth 37 travel through the spaces between the teeth 38 of member 13 until the upper faces of teeth 37 are below the highest point of beveled surfaces 39, rotation of the cap in the direction of arrow 41 causes the teeth 37 to engage the beveled surfaces 39 of the teeth 38. Thereafter, further rotation of the cap 12 in the direction of arrow 41 causes the teeth 37 to ride downwardly along beveled surfaces 39 until they reach the horizontal lower faces of teeth 38. As a result, cap 12 is moved axially as well as rotationally, and the O-ring seal 36 is squeezed against upper end edge 42 of the tubular member 13. Accordingly, as the O-ring seal 36 is pressed against the edge 42 a hermetic seal (see FIG. 4) is provided between the cap 12 and the tubular member 13. Engagement between the flat upper faces of teeth 37 and the horizontal lower faces of teeth 38 lock the cap 12 and member 13 together. To remove the cap 12 from engagement with the tubular member 13, the direction of rotation is reversed until the teeth 37 are located below the spaces between the teeth 38 and then the cap 13 is moved upwardly. Thus, it may be seen that a simple rotation of the cap 12 with respect to the tubular member 13 provides an axial movement of cap 12 with respect to member 13 which produces a squeezing of seal 36 and hence a hermetic seal.

Referring to FIGS. 3 and 4, cap 12 includes a bore 45 to which there is fixed the upper end of an elongated member 48 which extends axially past the teeth 37. The lower end of the elongated member 48 supports an assembly (see FIG. 2) adapted to frictionally engage the inside surface of the tubular'end 66 of a fuse 50. More particularly, the assembly includes an inverted cup 51 having a centrally located hole 52, a cylindrical elastic member 53 having an axial bore 54 and a flange 55 seated in the cup, a washer 56, and a screw 57. In the assembly, the head of the screw 57 abuts and supports the washer 56 against the elastic member 53, and its stem extends through the washer 56, the bore 54, and hole 52 into engagement with the elongated member 48. Thus, the elastic member is co-axially coupled to the end of the elongated member 48 and is capable of engaging and frictionally supporting a fuse.

Elongated member 48, preferably, is made from an insulating material and is long enough so that when the cap 14 is engaged with the tubular member 13, a fuse 50, engaged with the elastic member 53, will be seated within body 17 between the electrical terminals 14 and 16, as shown in FIGS. 2 and 5. Thus, to insert a fuse 50 into the fuse holder 10, cap 12 is removed from body 17, a fuse is pushed on to the lower end of member 48, and the cap and fuse are moved vertically into the body 17 until cap 12 can be locked on to the upper end of tubular member 13, as described above. To remove a spent fuse from holder 10, the steps described above are reversed.

Referring to FIG. 5, the bore 28 of terminal 16 supports a toroidal coiled contact spring 60. Prior to insertion of fuse 50 into holder 10, a cardboard washer 61, having a hole 62, is placed on the lower end of the fuse. The washer 61 guides the lower end 63 of fuse 50 into engagement with the toroidal spring 60. Similarly, prior to engagement of fuse 50 and member 48, a cardboard washer 67 having a hole 68 and a toroidal coiled contact spring 65 are applied to upper end 66 of fuse 50, as shown in F IG. 2. Toroidal contact spring 65, couples the contact end 66 of the fuse 50 to the terminal 14. Thus, when fuse 50 is being inserted into the fuse holder, the cup 51 of member 48 abuts the washer 67 and the washer moves the contact spring 65 downwardly into engagement with terminal 14. When the fuse 50 is being removed its body moves the contact spring 65 upwardly out of engagement with the terminal 14.

Referring to FIGS. 1 and 4, tubular member 13 rigidly supports a collar 69, which is used to secure the fuse holder 10 to, for example, the transformer housing 11. Since the housing may be located several feet below ground, cap 12 includes a hole 75 which may be engaged by the usual hookstick (not shown). The hookstick is used to disengage the cap 12 from the tubular member 13 when it is desired to replace a fuse, and to replace the cap 12 after a new fuse has been applied to the elastic member 53. It will be appreciated that only a simple rotational manipulation of the hookstick, after it is passed through hole 75, is required to produce axial movement of the cap 12 with respect to the member 13 so as to tightly lock or unlock the cap.

The flange 18 of terminal 14 and the bottom surface of the terminal 16 each includes a threaded hole within which threaded studs 70 and 71, respectively, are located. Studs 70 and 71 are used together with nuts 72 and 73, for connecting the fuse 50, electrically, to the apparatus it protects.

'From the foregoing, it may be seen that the fuse holder 10 provides a hermetically sealed enclosure for a fuse and that it includes a readily removable cap which enables a person to rapidly remove and replace spent fuses.

It is to be understood that the description herein of a preferred embodiment according to the invention is set forth as an example thereof and is not to be construed or interpreted as a limitation on the claims which follow and define the invention.

What is claimed is:

l. A holder for a fuse, comprising a. a body including first and second tubular members arranged in tandem,

b. a cylindrical metallic coupling engaging the lower end of the first tubular member and the upper end of the second tubular member to join the two members, said coupling being exposed on the interior of said body for electrical connection to a fuse and also being exposed on the exterior of said body, said coupling carrying a first terminal on its exterior surface for connecting said coupling to an electrical apparatus, whereby said coupling is adapted to serve as part of the electrical circuit between the fuse and an electrical apparatus,

c. cap means for closing off the upper end of the first tubular member and for inserting or removing a fuse from the body, and

d. a second electrical terminal mechanically coupled to the lower end of the second tubular member.

2. A holder for a fuse as defined in claim 1 wherein said upper end of the first member includes a plurality of annularly spaced teeth extending outwardly, and said cap means (c) has a plurality of annularly spaced teeth extending inwardly for engaging the teeth of the first member.

3. A holder for a fuse as defined in claim 2, wherein at least some of the teeth surfaces which engage each other are beveled in a way which moves the cap axially toward said first member upon relative rotation between the cap and first member. i

4. A holder for a fuse as defined in claim 2, wherein said cap carries seal means for providing a hermetic seal between the cap and said upper end of the first member.

A holder for a fuse as defined in claim 1, wherein said cap includes means for frictionally holding a fuse.

A holder for a fuse as defined in claim 1, wherein said lower end of the first tubular member includes a threaded section; wherein said upper end of the second tubular member includes a threaded section; and wherein the first electrical terminal and coupling includes a threaded end engaged with the threaded section of the first member and another threaded end engaged with the threaded section of the second tubular member.

A holder for a fuse, comprising: a body including first and second tubular members arranged in tandem,

b. a first cylindrical electrical terminal and coupling engaging the lower end of the first tubular member and the upper end of the second tubular member to join the two members,

cap means for closing off the upper end of the first tubular member and for inserting or removing a fuse from the body, and

d. a second electrical terminal mechanically coupled threaded ends, a first annular seal located between said flange and said lower end of the first member,

and a second annular seal located between said flange and said upper end of the second member,

5 thereby providing a hermetic seal between the first electrical terminal and said first and second members.

8. A holder for a fuse as defined in claim 7, wherein said flange has external electrical connector means.

9. A holder for a fuse as defined in claim 8, further including means for coupling the first electrical terminal to one terminal of a fuse and the second electrical terminal to the other terminal of a fuse.

10. A holder for a fuse, comprising:

a. a body including first and second tubular members arranged in tandem,

b. a first cylindrical electrical terminal and coupling engaging the lower end of the first tubular member and the upper end of the second tubular member to join the two members,

c. cap means for closing off the upper end of the first tubular member and for inserting or removing a fuse from the body, said cap including means for frictionally holding the fuse, said holding means comprising an elongated member extending from the cap, an elastic member adapted to be engageable with an end of the fuse, and means for securing the elastic member to the end of the elongated member, and

d. a second electrical terminal mechanically coupled to the lower end of the second tubular member. 

1. A holder for a fuse, comprising a. a body including first and second tubular members arranged in tandem, b. a cylindrical metallic coupling engaging the lower end of the first tubular member and the upper end of the second tubular member to join the two members, said coupling being exposed on the interior of said body for electrical connection to a fuse and also being exposed on the exterior of said body, said coupling carrying a first terminal on its exterior surface for connecting said coupling to an electrical apparatus, whereby said coupling is adapted to serve as part of the electrical circuit between the fuse and an electrical apparatus, c. cap means for closing off the upper end of the first tubular member and for inserting or removing a fuse from the body, and d. a second electrical terminal mechanically coupled to the lower end of the second tubular member.
 2. A holder for a fuse as defined in claim 1 wherein said upper end of the first member includes a plurality of annularly spaced teeth extending outwardly, and said cap means (c) has a plurality of annularly spaced teeth extending inwardly for engaging the teeth of the first member.
 3. A holder for a fuse as defined in claim 2, wherein at least some of the teeth surfaces which engage each other are beveled in a way which moves the cap axially toward said first member upon relative rotation between the cap and first member.
 4. A holder for a fuse as defined in claim 2, wherein said cap carries seal means for providing a hermetic seal between the cap and said upper end of the first member.
 5. A holder for a fuse as defined in claim 1, wherein said cap includes means for frictionally holding a fuse.
 6. A holder for a fuse as defined in claim 1, wherein said lower end of the first tubular member includes a threaded section; wherein said upper end of the second tubular member includes a threaded section; and wherein the first electrical terminal and coupling includes a threaded end engaged with the threaded section of the first member and another threaded end engaged with the threaded section of the second tubular member.
 7. A holder for a fuse, comprising: a. a body including first and second tubular members arranged in tandem, b. a first cylindrical electrical terminal and coupling engaging the lower end of the first tubular member and the upper end of the second tubular member to join the two members, c. cap means for closing off the upper end of the first tubular member and for inserting or removing a fuse from the body, and d. a second electrical terminal mechanically coupled to the lower end of the second tubular member, e. said lower end of the first tubular member including a threaded section, said upper end of the second tubular member including a threaded section, the first electrical terminal and coupling including a threaded end engaged with the threaded section of the first member and another threaded end engaged with the threaded section of the second tubular member, said first electrical terminal and coupling also including a flange located between its threaded ends, a first annular seal located between said flange and said lower end of the first member, and a second annular seal located between said flange and said upper end of the second member, thereby providing a hermetic seal between the first electrical terminal and said first and second members.
 8. A holder for a fuse as defined in claim 7, wherein said flange has external electrical connector means.
 9. A holder for a fuse as defined in claim 8, further including means for coupling the first electrical terminal to one terminal of a fuse and the second electrical terminal to the other terminal of a fuse.
 10. A holder for a fuse, comprising: a. a body including first and second tubular members arranged in tandem, b. a first cylindrical electrical terminal and coupling engaging the lower end of the first tubular member and the upper end of the second tubular member to join the two members, c. cap means for closing off the upper end of the first tubular member and for inserting or removing a fuse from the body, said cap including means for frictionally holding the fuse, said holding means comprising an elongated member extending from the cap, an elastic member adapted to be engageable with an end of the fuse, and means for securing the elastic member to the end of the elongated member, and d. a second electrical terminal mechanically coupled to the lower end of the second tubular member. 